Thermostatic switch



March 29, 1949. s. w. E. ANDERSSON 2,465,830

THERMOSTATIC SWITCH Filed July 30, 1946 2 Sheets-Sheet 1 VINVENTOR. PW/v ATTURNE Y or J Y I 6 B \N [11: 4 o 6 m| 7 M B Z V, Z I L m 2 March 1949- s. w. E. ANDERSSON 2,465,830

THERMOSTATIC SWITCH 2 Sheets-Sheet 2 Filed July 30, 1946 Hill-55V.

Patented Mar. 29, 1949 THERMOSTATIC swrrcn Sven W. E. Andersson, Evansville, Ind., assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application July 30, 1946, Serial No. 687,167

my Patent No. 2,338,563, entitled Thermostatic element, granted January 4, 1946.

No matter how perfect an air conditioner may be, it will, just like any other contrivance, afford no greater convenience than the nicety of its control. Furthermore, particularly in household appliances, stability and ease of installation are features of importance to the customer and contractor alike. It is, therefore, the object of my invention to provide a more sturdy control unit of the subject type which is easier to install, and which, when used with a proper air conditioner, enhances comfort by maintaining a steadier temperature in the premises served by the air conditioner.

This objective is achieved by quickening flow of room air in contact with a temperature sensing element having a large thin wall so that when a change from the desired temperature starts to take place, it is more quickly felt and countered by the control unit, and the unit itself is fastened on an outlet box in the wall so that the ends of the wires of an electric cable securely clamped in the outlet box can be simply directed into the control unit as it is placed on the outlet and the wires secured to the connectors without imposing any strain on the control unit.

The objective and manner of achievement are more fully set forth in the following description in connection with the accompanying drawings in which like reference characters denote like parts throughout the several views. The drawings, of course,'are only for the purpose of illustration and do not define the invention, reference being had for this purpose to the claims at the end of this specification. In the drawings:

Fig. 1 is a perspective view of a thermostatic control unit incorporating the novel features of the present invention and showing the flue at the side of the casing for continuously circulating air over the thermal responsive element.

Fig. 2 is a longitudinal sectional view of the thermostatic control unit showing the adapter plate for mounting the unit on an outlet box in the wall of a room or enclosure;

Fig. 3 is a sectional plan view on line 33 of Fig. 2 showing the clamp on the adapter plate for supporting the cable adjacent the unit;

Fig. 4 is a sectional view on line 4-4 of Fig.

3 showing the openings in the casing forming the 5 Claims. (Cl. 200140) 2 flue and the arrangement of the parts of the unit;

Fig. 5 is a sectional plan view on line 5-5 of Fig. 2 showing the swinging lever for operating the control elements and the bellows and springs for actuating the lever in opposite directions;

Fig. 6 is a sectional view on line 66 of Fig. 2 showing the pivotal mounting for the operating lever; and

Fig. 7' is a rear elevational view of the thermostatic control unit showing the slot through which the cable wires are drawn and the means for fastening it to the adapter plate.

The thermostatic control unit 6 is generally similar to that illustrated and described in my prior Patent No. 2,338,563 referred to above, and comprises a casing including a back plate or frame 7] and cooperating casing parts 8 and 9. The upper casing part 8 is supported on and overlies a bracket it connected to the back plate l by means of screws l i, see Fig. 2. A pair of depending selector switches l2 and i3 are also mounted on the bracket ill and the switches and casing part 8 are secured in place on opposite sides to the bracket by means of threaded sleeves extending upwardly from the switches through holes in the bracket and easing part and nuts l4 screwed onto the threaded sleeves. Push lever or handles it and it for the switches l2 and it extend up- Wardly from the casing part 8 for manual operation. As illustrated in Figs. 1 and 2 the casing part 8 has a depending skirt ll at its front and sides.

The casing part 9 is of channel shape with its upper edge underlyin the depending skirt ll of the casing part 8 and depending down to a bracket l8 attached to the back plate 1 adjacent its lower end by means of screws l9, see Fig. 4. The bracket l8 preferably is made of a suitable plastic and constitutes a wall or closure for the bottom of the casing and the casing part 9 is attached thereby by a screw 20 extending through an inwardly directed lip 2| on the casing part and screwed into the bottom of the bracket, see Fig. 2. Thus, the back plate 1, casing parts 8 and 9 and lower bracket it! are connected to each other to provide a unitary enclosed casing. A plastic front panel 23 is attached to the casing part 9 by means of screws 23a and mounts a thermometer T. As illustrated in Figs. 1 and 2, the bracket l8 has depending Walls and together with the lower end of the plastic front panel 23 form a chamber 22 below and outside of the enclosing casing.

An intermediate bracket 24 is attached to the back plate 1 by means of screws 25 and the bracket mounts the operating parts of the therarranged to be operated sequentiallyby an actuator in the form of a lever 33 mounted to swing about a vertical axis, see Figs. 2, 5 and 6. As illustrated in Fig. 6 the lever 30 is of generally rectangular form with a recess 3| at its rearward edge to adapt it to straddle a portion of the bracket 24. The lever 33 is mounted for swinging movement on a pintle 32 fixedly mounted in a portion of the bracket 24 by means of set screws 33. Adjustable bearings 34 on the lever 33 engage the opposite projecting ends of the pintle 32 to mount the lever 33 for swinging movement.

The lever 33 is swung in one direction or toward the switches 23 and 21, see Figs. 2 and 5, by

springs 33, and is swung in the opposite direction against the action of the springs by an expansible and contractable element or, bellows 31. The bellows 31 is mounted directly on the lever 33 by means of screws 33 and the bellows is positioned between the lever and an adjusting means on the bracket 24. The adjusting means comprises a screw 39 having a threaded engagement with a portion of the intermediate bracket 24 and a manually operable dial 43 mounted fast on the screw. Preferably, the screw 39 includes a second adjusting screw 33a rotatable therein and a pin 4| extends between the latter and a block 31a on the bellows 31. The pin 4| has tapered ends projecting into conical recesses in the screw 33a and block 31a to retain the pin in position. Dial 43 also includes an annular indicator card 43a of a suitable plastic material and marked on its outer periphery with indicia to indicate the temperature at which the lever 33 will operate the switch 23. The annular indicating card is clamped at its inner periphery between the dial and a smaller disk 43b covering the inner screw 39a. As shown in Fig. 4 the disks 43 and 40b are attached by means of screws 43c. Rotation of the dial 43 and screw 33 connected thereto will cause the latter to be moved axially and operating through a pin 4|, will move the lever 33 and bellows 31 mounted thereon with respect to the switches 23 and 21. The apparatus is initially adjusted by means of the'screw 39a and the annular indicator card 43:: may be turned relative to the dial 43 by loosening the screws 430 to adjust the dial to correspond with the temperature at which the switches 23 and 21 are operated.

An electric terminal block 42, see Fig. 4, is" attached to the back plate or frame I by screws 42a, see Fig. '1, and is spaced from one side of the casing to adapt wires W of a cable of wires to be drawn in and attached to binding posts 43 on the front of the block. An electric heating element 44 is also provided in the casing for continuously heating the interior thereof and the element is shown as of doughnut shaped form and positioned between the bellows 31 and forward part of the bracket 24 and surrounding the pin 4| and screw 33. The heating element may be of any suitable construction but preferably comprises an electrical resistance wire embedded in the doughnut shaped element composed ofv a suitable insulating plastic. While not shown, it will be understood that the terminals of the switches -|2, l3 and 23, 21 and the heating element 44 are interconnected with the binding posts 43 at the rearward side of the terminal block 42 to provide electric control circuits for the apparatus to be controlled.

The bellows 31 is connected by a capillary tube 45 to a thermal responsive element or bulb 43 in the chamber 22 below and outside of the enclosing casing. The bulb 43 contains a volatile liquid, such as methyl chloride, and being subjected to the ambient air produces a vapor pressure in the bulb 43, capillary tube 45 and bellows 31,corresponding to the temperature of the ambient.

In accordance with the present invention the bulb 43 consists of a closed generally cylindrical container having a metal wall of minimum thickness to facilitate the transfer of heat to the liquid therein and thereby increase the responsiveness of the thermostat to a maximum. In order to further increase the responsiveness of the thermostat the wall of the bulb 43 is corrugated to increase the heat transfer surface and also increase the resistance to deformation so that the wall may have a minimum thickness.

To further increase the responsiveness of the thermostat, the ambient air in the room or en- I closure is continuously circulated over the bulb 43. For this purpose a flue 53 is provided in the casing 3 directly above the bulb 43. As illustrated in Figs. 1 and 4 the flue 53 is formed by openings 5| in the bottom wall or bracket I3 of the casing 3 directly above the thermostatic bulb 43 and openings 52 in the casing part 3 adjacent its top. Thus, the flue 53 comprises the interior of the casing and includes an unrestricted path of flow between the side of the terminal block 42 and the wall of th casing. Also the side of the casing 3 adjacent the bulb 43 has openings 53 to supply ambient air to the flue 53 through the side as well as the open bottom of the chamber 2.2. As the air in the casing 3 is heated by the heating element 44 it will rise and cause a continuous circulation of air through the flue 55 and around the bulb 43. Thus, ambient air continuously circulates around the bulb 43 to render it immediately responsive to changes in the ambient temperature.

The present invention also includes an adapter plate 55 to facilitate the mounting of the thermostatic unit 3 on an outlet box 51 of usual construction in the wall 53 of a room 'or enclosure. The adapter plate 55 is connected to brackets 53 in the outlet box by means of screws 33, and the back plate 1 of the unit 3 is attached to the adapter plate by means of screws 3|, see Figs. 2, 4 and '1, threaded spacer bushings 54 being per-- manently attached to the front of the plate in any suitable manner to properly position the unit with respect to the wall 53. As illustrated in Figs. 2 and 3 the adapter plate 55 is cut and a triangular portion 32 of the plate folded back at an angle to the plane of the plate to project into the outlet box 51.

A clamp 33 cooperates with the angular portion 32 of the adapter plate 55 to hold an electric cable 34 adjacent the thermostatic control unit to relieve the wires W of the cable from any strain on the binding posts 43, see Figs. 2 and 3. In the illustrated embodiment of the invention the end of the folded angular portion of the adapter plate 55 has a narrow tongue 35 which projects through a slot 33 in the clamp 33 to provide a hinged connection at one end and the clamp is tightened against the cable 34 by means of a screw 31. The slot 33 formed by the folded backportion 32 of the adapter plate 55 together with a slot 89 in the back plate 1 of the unit, see-Fig. 7, provide an opening through which the wires W of the cable 64 may be drawn from the outlet box 51 into the interior of the casing of the unit 6. One form of the invention having now been described in detail, the manner of mounting the thermostatic unit and the operation of the unit is explained as follows.

It will be understood that when the parts of the thermostatic control unit 6 are assembled the terminals of the switches l2, I3, 25 and 21 and the heating element 44 will be connected by suitable conductors to the binding posts 43 at the rearward side of the terminal block 42. To mount the thermostatic control unit 5 the adapter plate 55 is first, connected to the front of the outlet box 51 by inserting screws 60 through holes in the plate and screwing them into tapped holes in brackets 59 in the outlet box until the heads of the screws are tightened against the front of the plate. The cable 64 is then positioned between the folded back portion 62 of the adapter plate 55 and the clamp 63 and the screw 61 tightened to clamp the cable in position.

The thermostatic control unit 6 is then mounted'on the adapter plate 55 by inserting screws 6| through the back plate 1 and screwing them into the threaded bushings 54. The ends of the wires W of the cable 64, previously drawn from the outlet box 51 into the casing of the unit through the aligned openings or slots 68 and 69 in the adapter plate 55 and back plate 1 of the unit, are attached to the binding posts 43. The casing part 9 is then positioned in place and attached to the bottom wall or bracket l8 of the unit. The dial 40 is turned manually by engaging the edge portion extending from the side of the casing with the finger to adjust the thermo stat to the desired temperature.

The heating element 44 being energized causes a thermosyphon circulation of the air in the room or enclosure through the flue 5G in the casing of the unit 6. As the openings 5| in the bottom wall or bracket I8, constituting part of the flue, are positioned directly over the thermal responsive bulb 46 the latter will be continuously subjected to a flow of ambient air and to any changes in the temperature of the air. Furthermore, because of the surface area of the bulb 46 and the minimum thickness of the wall of the bulb, due to the corrugated construction, the volatile liquid in the bulb is immediately responsive to changes in the temperature of the aim bient. As the temperature of the ambient air increases the vapor pressure of the volatile liquid in the bulb increases and when the temperature of the ambient air decreases the vapor pressure of the volatile liquid decreases. Such changes in the pressure in the bulb 46 are transmitted through the capillary tube 45 to the interior of the bellows 31. Upon an increase in pressure the bellows 31 expands to rock the lever 30 counterclockwise as viewed in Fig. 5 against the action of the springs 35 and upon a decrease in pressure in the bellows 31 the lever is rocked in a clock wise direction by the springs. Such movement of the lever 30 operates the switches 26 and 21 sequentially to controlcircuits through the wires W of the cable 64 as connected by the selector switches l2 and I3. By turning the dial 40 the rotary motion is converted to axial movement by the screw 39 and transmitted through the pin M to initially set the bellows 31 and lever 30 on which it is mounted with respect to the control switches 28 and '21 to increase or decrease the expansion of the bellows necessary to operate the switches.

It will now be observed that the present invention provides an improvedconstruction and arrangement of elements in a thermostatic control unit. It will also be observed that the present invention improves the responsiveness of the thermostatic control unit by corrugating the heat transfer wall of the thermal responsive element and continuously circulating ambient air over the element. It will still further be observed that the present invention facilitates the mounting of the thermostatic control unit on the wall of the room or enclosure to be conditioned and supports the electric cable adjacent the unit.

While only a single embodiment of the invention is illustrated and described it will be understood that changes may be made in the construction and arrangement of elements without departing from the spirit or scope of the invention. For example, the thermal responsive element may be positioned in the casing directly above the flue opening instead of outside and below the flue opening or the thermal element may be in a chamber separated from the heating element but enclosed in the casing. Therefore, without limiting myself in this respect the invention is defined by the appended claims:

What is claimed is:

1. Apparatus of the type indicated comprising a thermostatic control unit having an enclosed casing, an electric outlet box, an electric cable of individual conductor wires extending into the outlet box, and an adapter plate for connecting the casing of the unit to the outlet box and having an opening through which the wires of the cable may be drawn from the outlet box into the casing. v

2. Apparatus of the type indicated comprising a thermostatic control unit having an enclosed casing, electrical control means in the casing, a terminal block in the casing and spaced from one side thereof, an electric outlet box, a cable of individual conductor wires extending into the outlet box, and an adapter plate for connecting the casing of the unit to the outlet box and having an opening through which the wires of the cable may be drawn from the outlet box into the casing and attached to the terminal block.

3. Apparatus of the type indicated comprising a thermostatic control unit having an enclosed casing, electrical control means in the casing, a terminal block in the casing and spaced from one side thereof, an electric outlet box, a cable of individual conductor wires extending into the outlet box, an adapter plate for connecting the casing of the unit to the outlet box and having an opening through which the wires of the I cable may be drawn from the outlet box into the casing and attached to the terminal block, and a clamp on the adapter plate for holding the cable to prevent any strain on the connecting wires of the cable.

4. Apparatus of the type indicated comprising a thermostatic control unit havin an enclosed casing, electrical control means in the casing, a terminal block in the casing spaced from one side thereof, an electric outlet box, a cable of individual conductor wires extending into the outlet box, an adapter plate for connecting the casing of the unit to the outlet box, said casing having an opening in the rearward wall thereof, and said adapter plate having a flap folded outaaoaaso 7 wardly from the adapter plate to form a slot therein through which the wires of the cable may be drawn from the outlet box into the easing and attached to the terminal block, and a clamp on the folded flap of the adapter plate for holding the cable.

5. Apparatus of the type indicated comprising a thermostatic control unit having an enclosed casing, an electrical outlet box, a cable of individual wires extending into the outlet box, an adapter plate detachably fastened on the outlet box, said adapter plate having a flap folded outwardly therefrom to form a slot therein, a clamp cooperating with the flap to hold the cable, means for detachably mounting the thermostatic control unit on the adapter plate, and said casing having an opening adjacent the slot in the adapter plate to permit the wires of the cable to be drawn from the outlet box into the casing.

SVEN W. E. ANDERSSON. e

aamaucas crran The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,544,106 Scott June 30, 1925 1,610,479 Scott Dec. 14, 1926 1,656,949 Miller et a1. Jan. 24, 1928 1,931,484 Dicke Oct. 17, 1933 2,103,113 Hornung Dec. 21, 1937 2,144,576 Payne .4 Jan. 17, 1939 2,160,740 Hutchins May 30, 1939 Anderason Jan. 4, 1944 

